Correct way to respond to requests for payment when the build is not right

You decide to proceed with some building works - it might be a new equipment shed or perhaps a new shed for hay storage. But then there's an issue with what has been built and something isn't up to scratch. As a result, you are refusing to make payment until the defect is rectified.

To make things worse, the builder is demanding payment for the work and has issued a notice pursuant to the Building and Construction Industry Security of Payment Act 2009  seeking payment or a progress payment. What is the Building and Construction Industry Security of Payment Act 2009?  It is an Act which provides builders with a statutory entitlement to receive progress payments for a construction contract.